To fully understand the role of genetics and environment (biotic, abiotic and sociocultural) in the prostate cancer disparity experienced by African-American men, this paper examined the rates of prostate cancer among African-American men and one of their ancestral populations in west Africa. Data sources were from the World Health Organization (WHO) and reported hospital records in the literature. Based on the WHO's worldwide cancer data, west African men have much lower prostate cancer incidence and mortality compared to African-American men. For example, compared to Nigerian men, African-American men are >10 times likely to develop prostate cancer and 3.5 times likely to die from the disease. However, contrary to the global ranking by WHO, there is documented evidence in the literature indicating that prostate cancer in at least one west African country is similar to rates found in the United States and in Caribbean Islands. To better address prostate cancer disparity, future studies should study populations and subgroups from central and west Africa, the original source population for African Americans.